It was not the usual roundup of environmental activists saying the sky is falling. Instead, it was the biggest bankers and insurance companies calling for massive investments in clean energy lest we — and they — pay in massive damages from climate change.

“It’s the issue of our day,” said former Treasury Secretary Robert Rubin.

“The costs of another Sandy will grow from $19 billion to $90 billion,” said J. Eric Smith, the CEO of Swiss Re Americas.

Lisa Carnoy, head of global capital markets for Bank of America Merrill Lynch, exhorted her colleagues to fund clean energy projects until “every blue chip company in the S&P and . . . every investment manager has a green energy bond.”

They all spoke last week at the Investor Summit on Climate Risk, a forum of about 500 people sponsored by the UN and Ceres, the Boston-based coalition of investors, industries, and environmental groups that has sought for 25 years to engage big business in environmental protection and the climate change battle. The gathering offered the best evidence to date of corporate capital being thrown into the fight.

In the last two years, Bank of America, Goldman Sachs, Wells Fargo, and Morgan Stanley have announced goals to finance and invest in renewable energy projects, transmission lines, energy efficiency and storage, and transportation, water, and waste projects. Combined with an earlier commitment by Citi, those institutions have pledged a total of $180 billion by 2022. Annual global investment in “green bonds” for renewable energy and climate mitigation projects reached a record $10 billion last year.

As much money as that is, it is only the first drop of the shower needed to cool down the planet. Global clean energy investment was $254 billion last year, according to Michael Liebreich, CEO of Bloomberg New Energy Finance. But the International Energy Agency has said that $36 trillion of clean energy investment, or $1 trillion a year, is required by 2050 to keep the rise of earth’s temperature under 3.6 degrees Fahrenheit. The UN’s Intergovernmental Panel on Climate Change, in a draft report leaked last week to the media, estimates that at the current pace of emissions and lack of global response, greenhouse gas production will not be controllable by current technologies in 15 years.

Armed with reams of data presented at the conference, Ceres president Mindy Lubber and Christiana Figueres, executive secretary for the UN Framework Convention on Climate Change, called for the corporate world to reach that $1 trillion a year. Ceres in particular would like to see a doubling of investment to $500 billion by 2020 and $1 trillion by 2030.

Cecilia Reyes, chief investment officer for the Zurich Insurance group, said climate change has become a “systemic risk factor” in the investment world, one that is taking an increasing dim view of the infrastructure of the fossil fuel industry. For instance, she and several other speakers warned that if enough solar and wind farms come on line to cause power companies and governments to leave coal in the ground, coal-fired power plants will increasingly become “stranded assets.”

With global wealth last year at a record $241 trillion and headed to an estimated $334 trillion by 2018, the money is out there to retool for climate change, Liebreich said. “It’s all about the will to do it,” he said. “Up to now, some things have not been helpful, such as the US not having a climate policy because of Congress. But increasingly investors are understanding fossil fuel industry as being a low-performing and increasingly unpopular industry. People are understanding that cost of solar has come way down and the cost of wind is coming way down. If we get to where people see all of this as a business opportunity we have a chance.”

The question is when we will take the chance. Clearly we must or else. After the conference was over, Lubber said, “I know the number sounds ridiculous, $1 trillion a year. But what is more ridiculous, that or the planet we’re going to leave behind if we do not invest now?’’